Method of controlling microorganisms by means of organic thiocyanates



United States Patent This invention is concerned with a method of controlling the growth of microorganisms such as fungi, bacteria and the like by means of certain phenacyl thiocyanates. The invention also pertains to the formulation, use and application of microbiocides incorporating as their active constituent at least one of the aforesaid phenacyl thiocyanates.

The present invention is predicated on the finding that I: certain organic thiocyanates which are characterized by the presence of both a keto and a thiocyanate function exhibit a high degree of biocidal activity and are especially effective in controlling the growth of microorganisms such as fungi, bacteria and the like. It is accordingly a primary purpose" and object of this invention to provide a method for controlling microorganisms by means of the aforementioned organic thiocyanates. It is a further object of the invention to provide microbiocidal compositions containing as the active principal thereof at least one of the aforementioned organic thiocyanates. Other objects and purposes will become manifest as the description proceeds, V

The dual function thiocyanates which are suitable for controlling microorganisms as above described can' be generally depicted by the following formula:

rat-Q0 O-GHPSCN it: in wherein at least one of R R andR designates hydrogen; a lower alkyl radical e.g. methyLethyl, n-propyl; isobutyl, n-butyl, sec-butyl and the like; an isothiocyanate radical, an amino group or a nitro group. e

Examples of structures includedwithin the ambit of the general formula include the following lists of compounds:

NGSQ-C O-GHz-SCH Compound 5 9-0 o-orn-son n- 3110 mo-O-o o-om-son Compound 6:

Compound 10:

Compound 11 Compound 12:

Compound 13:

Compound 14:

Compound 15:

Compound 16:

Compound 17:

Certain of the thiocyanates as contemplated herein are known entities, the description and preparation of which may be found in the chemical literature. In general-,these compounds are formed by reacting a phenacyl halide bearing the appropriately substituted aromatic ring with an alkali metal thiocyanate. A typical synthetic procedure comprises refluxing an alcoholic solution of the requisite phenacyl halide with an excess of po'tas'siurn toxicants when placed in contact with growing fungus or bacteria. In this procedure 1 oz. bottles are partially filled with 10 ml. of malt or nutrient broth and capped Patented Dec. 7, 1965" with aluminum foil, sterilized and maintained for the wherein R R and R are selected from the class contest. A compound is then injected by means of a syringe sisting of hydrogen, lower alkyl thiocyanate, amino and through the foil and into the broth followed by inoculanitro. tion with a water suspension of spores. The bottles are 2. A method of inhibiting the growth of microorgansealed and held for one week before the results are evalu- 5 isms which comprises applying thereto a small but effecated. tive amount of a phenacyl thiocyanate of the following A foliage fungicide test is conducted in order to ascerformula: tain the protectant action as well as eradicant and leaf systemic action of the test compounds. The particular type of action which is produced by the test compound is determined by evaluation tests. Pinto bean plants are sprayed with various concentrations of the toxicant 3. A method of inhibiting the growth of microorganand, after y the Plants are inoculated With bean isms which comprises applying thereto a small but effecl'ust P y mildew P Rust infection requires tive amount of a phenacyl thiocyanate of the following an overnight treatment in a moisture chamber following f rmula: inoculation. CH

Weathering tests were carried out for the purpose of 3 determining how long the compound remained in contact with the plant. Toxicants which are volatile or undergo hydrolytic reactions or otherwise become inacti- E vated are not suitable as commercial fungicides. Tests to determine the weathering qualities of the herein contemplated toxicants were carried out in a humidity or mois- A method mhlbltmfg the growth of mlcroorgan ture chamber in which pinto bean plants inoculated with Whlch comprises applymg, thereto a Small but f rust powdery ild are sprayed with the Particular tive amount of a phenacyl thiocyanate of the following compound under test. The length of time of the test formula: comprises 2 days and 2 nights in the moisture chamber.

The results of carrying out the above described tests, (FCHFSCN using the thiocyanate toxicants of this invention, are I reported in the table below. 0115 Table In vitro Foliage tests Weathering Tomato Comgrey pound Aspergillus Penicill- Bean Bean N. corn l mger ium P.p.m. rust Mildew leaf Rust Mildew spot blight The activity of Compound 8 was determined by the agar plate test. This procedure consists of placing 0.1 g. of the compound ma 0.5 ml. micro beaker which is then inserted in a petri dish of hardened potato dextrose agar. The m croorganism spores are dusted over the agar surface and after approximately 1 week the growth of the fungus is observed and the results recorded as percent control. The following data was obtained using Compound 8: Staphylococcus aureus, 100 p.p.m.; Erwim'a amylovora, 500 p.p.m.; Escherichia coli, 500 p.p.m.

100=n0 pustules or mildew. ++++=75 to 100% control. +++=50 to 74% control.

Numbers in parentheses indicate partial fungus inhibition at that concentration in p.p.m.

We claim:

1. A method of inhibiting the growth of microorganisms which comprises applying thereto a small but effective amount of a phenacyl thiocyanate represented by the following formula:

I l: f t: 75

5. A method of inhibiting the growth of microorganisms which comprises applying thereto a small but effective amount of a phenacyl thiocyanate of the following formula:

5 6 6. A method of inhibiting the growth of microorgan- References Cited by the Examiner isms which comprises applying thereto a small but effec- UNITED STATES PATENTS tive amount of a phenacyl thiocyanate of the following 2 213 216 9/1940 Hester 167 30 Emma 5 2,462,433 2/1949 Searle 260-454 2,923,658 2/1960 Regel et a1. 167-30 -O (Pom-SON 2,965,537 12/1960 Rosen 167-30 3,085,045 4/1963 Lukes et a1. 16730 7 A h d f h b t th Wth f 3,097,130 7/1963 Regel et a1. 16730 me 0 0 1n 1 1mg e gro o microorgan- I isms Which comprises applying thereto a small but effec- 10 OTHER REFERENCES tive amount of a phenacyl thiocyanate of the following C.A., volume 42 (1948), pages 2386-2387. formula: Grove et 211.: App. BioL, vol. 34, No. 8, September 1946, pp. 113-124. GET-SUN 15 JULIAN s. LEVITT, Primary Examiner.

hog MORRIS o. WOLK, LEWIS GOTTS, Examimers.

UNITED STATES :PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,222,248 December 7, 1965 George E. Lukes et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as t d b l E fm?1 1? ines 46 to 48 for that portion of Compound 1 reading "-SCH" read SCN lines 50 to 53, for that portion of Compound 2 reading "CH read H same column 1,

lines 55 to 58, for that portion of Compound 3 reading "SCH" read SCN column 3, lines 72 to 75, for that portion of the formula reading "-CH" read CO- Signed and sealed this 27th day of September 1966.

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner of Patents 

1. A METHOD OF INHIBITING THE GROWTH OF MICROORGANISMS WHICH COMPRISES APPLYING THERETO A SMALL BUT EFFECTIVE AMOUNT OF A PHENACYL THIOCYANATE REPERSENTED BY THE FOLLOWING FORMULA: 